Conventional rearview mirrors provided on the windshield of virtually every new vehicle sold in North America typically include a single flat rearwardly reflective surface providing an undistorted but limited field of view to the vehicle's rear. This therefore results in the so-called "blind spots" to either side of the vehicle's flanks where the driver checking his mirror cannot see other vehicles. Shoulder checking is the only means of confirming that the blind spots are empty of vehicles, making it safe to change lanes. Shoulder checking requires the driver to take his eyes off the road and is itself therefore somewhat hazardous.
Various mirror constructions have been proposed to overcome the limitation of conventional mirrors but most of these efforts have failed due either to a cumbersome structure, excessive distortion of the field of view, cost, poor ergonomics and poor aesthetics. Perhaps as importantly, mirrors offering an enhanced rearward field of view are not as yet widely offered as original equipment on new vehicles, which, if they were, would lend greater credibility to the use of these devices for enhanced vehicle safety. Moreover, a large part of the reason such mirrors are not offered as original equipment from manufacturers is the lack of a suitable product which overcomes the deficiencies of known after-market products.